Link chains are disclosed in DE 198 36 374 C1, in DE 100 33 726 C1 and in DE 1 752 557 AI. In addition, DE 203 04 437 U1 shows a link chain where the inside of an aperture is provided with a coating in order to receive a stud bolt.
U.S. Pat. No. 6,666,013 B2 discloses a chain where at least a portion of the chain, for example a surface, is coated with DLC (diamond-like carbon) with preferably metal particles being formed in the DLC hard material layer. The disadvantage of such a coating is that the DLC layer has to be applied by means of a CVD process where the amorphous carbon for the DLC layer is deposited from a chemical gaseous phase out of hydrocarbon ions reacting with fixed carbon. In this process, however, hydrogen is formed, so that it cannot be excluded that the hydrogen released by the hydrocarbon ions in the CVD process may cause a hydrogen embrittlement in the chain material. Moreover, such a CVD process requires a compact and expensive process and plant engineering and has therefore, not proven itself successful in practice for the finishing of chain links.